Electricity From The Wind

Mauritius Times – 60 Years Ago

By Peter Ibbotson

According to Mr Profumo when he answered a question in the House of Commons from James Johnson recently, the development of a cement industry in Mauritius is hampered by a lack of local fuel supply.

To increase the supply of electricity, the Central Electricity Board is undertaking a big programme of development which the P.R.O. detailed in a recent communiqué. Extensive works have been authorised in various parts of the island. The Eau Bleue scheme is due to come into commission at the end of 1958. The La Ferme and Tamarind schemes are due to be in commission by the end of 1958 or the beginning of 1959. When these three schemes are fully operating, a further 20 million units will be available. Two further schemes are under active consideration, one to be begun in 1959 or 1960, and the other two years later. Both new works will give employment to a large number of men and will add between 15 and 20 million units per year to the island’s electricity supply.

Tamarind Fall Hydro Power Station

All these schemes, the three under construction and the two under consideration, are hydro-electric. All rely on making full use of the island’s water supplies. Yet agriculturists are not all satisfied that the construction of these hydro-electric works is in the best interest of the island’s agriculture. Some critics allege that diverting water to reservoirs will leave less available for irrigation and may harm the basic industry – agriculture.

However, the experts of the C.E.B. can no doubt allay the fears of the agricultural jeremiahs. When the new schemes are in operation, however, will there be enough electricity regularly available for a cement factory – should one be established? Will the completion of the three schemes at Eau Bleue, La Ferme and Tamarind River give enough power for a cement works, or must we also await the completion of the two major schemes now under consideration before there will be enough power for a factory which will make enough cement from coral sand, clay and bagasse ash to cut the import of cement from abroad?

Meanwhile, the C.E.B. says, the diesel power station at Port Louis must remain in use to augment the supply at peak load hours and to ensure supply during drought periods.

Has, however, the C.E.B. given any consideration to alternative means of electricity generation? Hydro-electric schemes are not the only means available in Mauritius to generate electricity; and it would be interesting to know if consideration has been given to other means.

What, is a natural question, are these other means? They are all natural means; the winds, solar radiation, and the energy from the tides. All can be harnessed to provide electricity; and while perhaps they would be unsuitable to rely on entirely, they could provide a useful auxiliary means of producing electricity, to supplement the supply from the hydro-electric schemes in the same way that the diesel power station now augments the regular supply.

Mauritius is fortunate in having a long period of steady winds throughout winter. The South-East Trade Winds blow steadily, at moderate strength, all the winter through. Moderate strength is a speed of some 13 to 18 miles per hour. Sometimes their speed rises to strong, that is to about 25 to 31 miles per hour; occasionally they reach gale force, 39 to 46 miles per hour, steadily from one direction in winter. In summer, the direction changes, but the speed is still fairly constant and reliable.

This wind can be utilised, I suggest, to generate an auxiliary supply of electricity. Not a huge supply, I emphasise, but a supply sufficient to add appreciably to the hydro-electric power now (or soon to be) available.

Algeria provides an example of a country where the wind is harnessed to provide extra electricity. The nationalised electricity supply company of Algeria, Electricité et Gaz d’Algérie, has for eight years been investigating the possibility of wind-generated electricity and wind-mill is presently being built to provide tests. It is on a windy hill near the sea, about six miles from Algiers, 860 feet (about 263 metres) high. This experimental windmill has a maximum output of 200,000 units per year. i.e. a capacity of 100 kilowatts; not a large output, but large enough to serve as a guide to the possibility of building more and larger windmills to generate more power.

This maximum output is achieved at a windspeed of 30 miles per hour; at higher windspeeds the blades of the windmill automatically change pitch so that the same output is reached. At lower speeds, less power is generated. 

The experimental windmill follows the principles of Mr Andreau of Paris. Any wind-driven generator must have a rotor, driven by the wind, whose rotation is transmitted to an electric generator. Andreau’s windmill has two blades to its rotor. These blades are hollow and open at their tips. The rotor hub and the two supporting it are also hollow. The wind causes the rotor to rotate, air is flung out from the open tips of the two rotor blades, and suction is thus created. A huge volume of air is drawn up the hollow tower (at 30 miles per hour windspeed, the volume is actually 58,500 cubic feet or 1,656 metres per minute) and through a vertically-shafted axial-flow turbine near the bottom. The turbine drives an A.C. generator carried below it on the same shaft. It is a three-phase alternator, of the synchronous induction type, generating power (in the particular windmill at Algiers) at 415 volts.

The power generated by the windmill will be fed into the country’s supply, since the experimental windmill has been sited near a high tension line carrying 10,000 volts. The windmill is 100 feet (30 ½ metres) high. The rotor blades are 40 feet (12 metres) long and weigh 1,600 pounds (725 kg) each. They can be oriented to follow changes in wind direction. Since the control gear and  generating plant are at ground level, maintenance is easy, and fluctuations in wind speed are damped  out by the very flexible drive through a long column of air.

The Algerian experiment is being watched with interest. Meanwhile it would be instructive to learn whether the C.E.B. has considered the possibility of wind-generated power as an auxiliary source. May we hear from Mr Borland?

Friday 9^th August 1957

* Published in print edition on 2 February 2021